We propose to establish a Center of Excellence on childhood obesity research and training, based on a transdisciplinary systems science framework and methodologies. We propose to use systems modeling approaches with integrated application of spatial analysis. Modeling will be guided by behavioral models and basic science regarding food intake and body weight regulation to study the complex determinants of childhood obesity and the impacts of environmental and policy interventions. We will undertake epidemiological research to study the cascading influences of macrosocial environmental factors on individual-level behaviors and biology using existing and new data from large cohorts of children and their families in the U.S. and in China. In proposed projects we synthesize epidemiological methods and designs with basic sciences to explore how social, environmental and individual factors relate synergistically to energy balance related behaviors to differential epigenetic programming. We will also evaluate a novel multilevel food access intervention that can become a model of effective and sustainable community-based interventions and policy changes, focusing on an urban low-income population at high risk of obesity. By combining features of previous effective intervention approaches, within a broader systems framework, we hope to make desirable, food choices more accessible, sustainable, and cost effective. In addition, we will encourage and support developmental research to develop and evaluate environmental and policy interventions in the proposed Pilot Study Core. We will establish a computational workshop for systems modeling and GIS-based investigation (Research Resource Core and Training Core) that will provide an infrastructure to advance the Center's training and research mission. We will train a new cohort of investigators at different career stages in emerging system-science theories and methods. Over 40 well established investigators from leading US and international institutions bring transdisciplinary expertise to bear in highly relevant areas. The Center will build upon a solid research and training base with ongoing NIH funded projects directly related to childhood obesity and systems analysis.